Abstract

Co-registered optical coherence tomography (OCT) and video microscopy of the rat somatosensory cortex were acquired simultaneously through a thinned skull during forepaw electrical stimulation. Fractional signal change measured by OCT revealed a functional signal time course corresponding to the hemodynamic signal measurement made with video microscopy. OCT can provide high-resolution, cross-sectional images of functional neurovascular activation and may offer a new tool for basic neuroscience research in the important rat cerebral cortex model.

Precise registration of OCT imaging to the region of functional activation. The OCT scan is directed in the region of interest measured with video microscopy (A, B). Horizontal bars in B mark the activated and baseline time windows used to generate the functional map in A. Structural OCT imaging (C) visualizes the skull (S), surface vasculature (V), and meningeal layers, including the dura mater (D). Percent variation maps extracted from the multiple trial data set reveal smaller vessels above the dura, while highlighting the low signal fluctuation in the skull compared when with the cortex.

Functional OCT in the rat cortex. A fractional change map (A) demonstrates positive (warm colors) and negative (cool colors) changes in OCT signals during stimulation. Temporal sequences (B) reveal the presence of highly localized regions of activation in the cortex that persist throughout stimulation. Further analysis of the localized regions of interest (C, D) shows a functional OCT time course that correlates well with that of the intrinsic hemodynamic optical signal but with both positive- and negative-going responses. The horizontal bars in D indicate the time windows used to generate the functional map (A, B, C).